Boring tool



clc. KOELN.

BORING TOOL.

APPLICATION FILED IAN. I7, I9I2.

1,438, 53, Paten ted Dec.12,1922.

E 7 a a i y .7 E a i A? 1e? m 1% 10 17 i 10 i M @1 Patented Dec. 12, 1922.

CHRISTIAN C. KOELN, OF ST. LOU IS, MISSOURI.

BORING- TOOL.

Application filed January 17, 1921. Serial No. 437,813.

To all whom it may concern:

Be it known that I, CHRISTIAN C. KOELN, a citizen of the United States, and residing at St. Louis, Missouri, have invented the new and useful Improvement in Boring Tools, of

which the following is a specification.

This invention relates to tools and more particularly to boring tools. In some classes of tools, such as boring tools, a cutter isused which has cutting edges at its ends adapted for cooperation with the work to form therein a hole of a given diameter as determined by the distance between the cutting edges. Accordingly the cutting edges are accurately ground in order to form the hole with the required accuracy, and in most classes of work, even slight variations cannot be toler ated. Of course, the cutting edges of even high speed steel will become dull, but where sharpening is attempted, in such cases the grinding operation will reduce the distance between the cutting edges so that a hole of the desired diameter cannot be bored.

In order to permit grinding of the cutting edges while still maintaining the proper distance therebetween, mechanical adjustment is resorted to; this, however, presents mechanical difficulties and requires a divided cutter subject to errors and not as satisfactory as a one-piece cutter in which the cutting edges are connected by a body of metal.

One of the objects of this invention, therefore, is to provide a cutter in which the cutting edges are on the same piece of metal and, therefore, connected but whereby the cutting edges may be expanded.

Further objects will appear from the detail description taken in connection with the accompanying drawing, in which:

Figure 1 is a side elevation of a boring tool showing the application of an embodiment of this invention;

Figure 52 is a section on the line 2-2, Figure 1;

Figure embodying this invention;

Figure 4 is a side elevation of Figure 3:

Figure 5 is a section on the line 5-5, Figure 4; to Figure 6 is a face view showing another cutter embodying this invention;

Figure 7 is a side elevation of Figure 6;

Figure 8 is a section on the line 8-8, Figure 6;

Figure is a face view showin a cutter p 9 is a face view of a cutter showing another embodiment of this invention; and

Figure 10 is a section on line 10-10, Figure 9.

Referring to the accompanying drawings, and more particularly to Figures 1 and 2, 1 designates a boring bar of any suitable construction which is slotted to receive a cutter 2 which is held in place by a gib 3 and an ordinary taper pin 4. The general construc tion of such a cutter is well known in the art and further detail description thereof is, therefore, unnecessary.

Referring now to Figures 3, 4: and 5, the cutter comprises a body 5 of a malleable material, that is, one capable of being extended or shaped by beating with a hammer or by transverse pressure; a good material for such purpose is the ordinary cold rolled steel. This body joins a pair of cutting edges 6 which may be formed on any suitable parts 7 constructed of any suitable material, such as high speed steel. These parts 7 may be permanently secured to the body 5 in any suitable manner as by providing the parts with tongues 8 taking into corresponding grooves in the body and the body may then be pressed over the tongues so as to form in effect an integral structure with the parts 7.

The malleable body 5 is undulatory or tortuous in form and is, therefore, provided with undulations extending therealong and comprising hills 9 and valleys 10. These undulations be formed in the surface in any suitable manner as by forging.

Assuming now that the cutter has its cutting edges definitely spaced so as to bore a hole of a given diameter and assuming that the cutting edges havebecome dull and it is desired to grind the same but still maintain the proper spacing of these cutting edges; the procedure is then as follows: The cutter being removed from the boring bar is subjected to transverse pressure applied at its body part and on the undulationsso as to cause pressure flow of the material of the body and by rectification or straightening of the same. to cause expansion of the edges so as to space these edges further apart. This be accomplished by placing the cutter on an anvil and hammering down on the hills '9 so as to flatten them out or by hammering in the valleys 10 so as to spread. them still further; either of these operations will cause a pressure flow of the body metal and extension of the body lengthwiseso as to cause the desired expansion of the cutting edges. ()rdinarily this expansion need only be a few 2 messes thousandths of an inch and even a small amount offpressure will cause the desired extension. After the desired extension has been obtained so that the edges will beexpanded beyond their normal spacing, these edges can be reground so as to sharpen the cutter and this grinding can be continued until the cutter is ground down to the proper, spacing of the cutting edges."

In order, to permit extended hammering on the undulating body, the side edges there of are, beveledasshown at 11 which will com pensatej for transverse fiow'of the metal and prevent the extension of burrs laterally; accordingly even repeated hammering or working on the body will still present smooth and uninterrupted side faces 12, so that the cutter can fit properly in the slot in the boring. bar I l and against the 3. When the cutter is in place iii the boring bar, the body 5,will be whollywithin the, bar'as shown in Figure' l so, that the parts 7 will bedir ectly supported the bar whereby. no excessive strain will beplaced on thejoints formed be tween hese pirtslf C l Of ou e, b readilyaccomplished because the normalproje c tion, of'the cutting edgesb eyond the botingib aris'onlyia small fractional portion of an inch.

Referringito. Figures 6, 7, and 8, the body isdivided intotwo parts so as to provide legs 13 connecting the. euds'fof the body to which are fastened ,the cutter parts 7, the tongues 8 being in this case on the body while the grooves are inthe. cutter parts, and accordingly these. cutter parts may be connected .toIthebodyby pressure joints formed hy compressingfthe cutter parts an untempered condition on the body, these cutter parts being, subsequently hardened. In this embodiment, each leg is made undulatory or tortuous by providing hills 9 and valleys 10 therein as in the preceding embodiment. The undulations may be differently formed. Thus, while in the embodiment shown in Figures 3, and .5 the hills are directly opposite in the legs 13, Figures 6, 7 and 8, the hill on one side of the leg is opposite a valley on the other. It is, of course, obvious that in the. embodiment shown in Figures 6, 7 and 8 the bar may also be extended by pressure appliedto, the malleable body. lnthis case, howeven not only can the extension be greater but the leading andlagging edge plortionsof thecutter edges can be separatedly adjustedas the legs are capable of in dependent extensions. Qf course, in this embedinient the edges are again beveled as shown at 14 to prevent the formation of burrs.

In the embodiment shown in Figures 9 and 10, the m lleable body 15' is undulated as in Figures 3, {l and 5 butthe cutting edges are Ifprmed by" inserts It; set into recesses in the ma leable bek ya ltl se red l sseill. n

. It will, therefore, be seen that the. invention accomplishes its ob ects. A cutter is provided which is capable of extension so as to expand the cutting edges, at the same time always maintaining a permanent connection between these cutting edges. In practice the cutting edges may be repeatedly expanded in order to permit repeated grinding with the result thatthelifeof the cutteris'enorm s yinc ea e It is obvious that various changes may be made in details within the scope of the appended claims without departing from the spirit of this invention; it is,.there fore, to be understood that this invention is not to be limited to the specific details shownand described.

Having thus described the invention, what is claimed is:

1. In a tool, a cutter having cutting edges, and a tortuous malleable body joining said'edges adapted by rectification thereof to cause expansion of said edges.

In a tool, a cutter having cuttingedges and a malleable body joining said edges and provided with undulations in its surface, adapted by straightening of said undulations to cause expansion of said cutting edges. I

In a tool, a cutter having cutting edges and a malleable body joining said edges, said body having a projection adapted by pressure flow ofthe material thereof into said body to cause expansion. of said edges.

4. In a tool, a cutter having cutting edges and a malleable body joining said edges, the side edges of said body being beveled, whereby said body may be extended by flow of the metal to cause expansion of said ecges, the bevel compensating for the trans verse flow of the metal.

5. In a tool, a cutter having cutting edges and a malleable body joining said edges, said body being deformed for'extensionfby longitudinal pressure flow of the body metal in order to cause expansion of said edges, and the side edges of said body being beveled adjacent the deformation thereof.

6. Ina tool, a cutter having cutting edges and a malleable body joining said'edges, said body having independent portions constructed and arranged for independent extensions in order. to cause expansions of said edges at their leading and lagging tips respectively.

7 In a tool, a cutter having cutting edges, and a body joining said edges and split longitudinally into malleable elements which are adapted upon extension thereof to cause expansion of said edges.

8. In a tool, a cutter having cutting edges, and a body joining said edges and comprising tortuous malleable elements, adapted by rectification thereof to cause expansion of said edges. I

9. In a tool, a cutter having cutting edges, and a body joining said edges and split longitudinally into malleable elements which are adapted for independent extensions to cause expansion of said edges at their lagging and leading tips respectively.

10. In a tool, a cutter having cutting edges, and a malleable body joining said edges, said body having transverse undulations, substantially as and for the purpose set forth.

ll. In a tool, a cutter having cutting edges, and a malleable body joining said edges and split longitudinally into malleable elements, said. elements having undulations codirectional With the cutting edges.

In testimony whereof I afiix my signature this 30th day of November, 1920.

CHRISTIAN C. KOELN. 

